Question

我希望能够使用<core-ajax>渲染一个远程集合：

<rendered-collection url="/api/items">
  <custom-element value="{{ _it_ }}"></custom-element>
</rendered-collection>

其中<rendered-collection>类似于：

<link rel="import" href="/core-ajax/core-ajax.html">

<polymer-element name="rendered-collection" attributes="url" noscript>
  <template>
    <core-ajax url="{{ url }}" response="{{ collection }}" auto handleAs="json"></core-ajax>
    <template repeat="{{ _it_ in collection }}">
      <content><!-- cannot be used like that unfortunately --></content>
    </template>
  </template>
</polymer-element>

我意识到这不是<content>应该如何工作的，而且我仍然需要将模型注入其中。

我见过answers建议在JS中检索内容的节点：

<style>
  ::content > * {
    display: none;
  }
</style>
<content id="content"></content>
...
<script>
  Polymer('rendered-collection', {
    attached: function () {
      this.contentNodes = this.$.content.getDistributedNodes();
      // then...how do I inject models from the collection into the nodes?
    }
  });
</script>

最好的方法是什么？

Answer 1

如果我正确理解您的用例，您希望<rendered-collection>的子项描述集合中每个项目的呈现。这正是<template>的用途。因此，如果我们建议使用<rendered-collection>，那么：

<rendered-collection>
  <template>
    <h2>{{name}}</h2>
  </template>
</rendered-collection>

然后我们可以使用一些模板来渲染它：

<polymer-element name="rendered-collection">
<template>
  <content></content>
</template>
<script>
  Polymer('rendered-collection', {
    collection: [
      {name: 'alpha'},
      {name: 'beta'},
      {name: 'gamma'}
    ],
    ready: function() {
      this.bindTemplate();
    },
    bindTemplate: function() {
      // user-supplied template
      var t = this.querySelector('template');
      // optional, but supplies fancy expression support
      t.bindingDelegate = new PolymerExpressions();
      // repeat over the entire model
      t.setAttribute('repeat', '{{}}');
      // set the model to our collection
      t.model = this.collection;
    }
  });
</script>
</polymer-element>

http://jsbin.com/kedig/1/edit

Answer 2

下面的代码似乎有效，但我希望对此解决方案有反馈意见，这种解决方案感觉很糟糕且可以改进：

<rendered-collection url="/api/items">
  <custom-element value="{{ _it_ }}"></custom-element>
</rendered-collection>

与

<polymer-element name="html-render" attributes="html model">
  <template></template>
  <script>
    Polymer({
      htmlChanged: function() {
        var tmpl = document.createElement("template");
        tmpl.setAttribute("bind", "");
        // WARNING: Potential XSS vulnerability
        tmpl.innerHTML = this.html;
        tmpl.model = { _it_: this.model };
        this.shadowRoot.appendChild(tmpl);
        // Needed ?
        Platform.performMicrotaskCheckpoint();
      }
    });
  </script>
</polymer-element>

<polymer-element name="rendered-collection" attributes="url">
  <template>
    <content id="content"></content>
    <core-ajax url="{{ url }}" response="{{ collection }}" auto handleAs="json"></core-ajax>
    <template repeat="{{ item in collection }}">
      <template repeat="{{ node in contentNodes }}">
        <html-render html="{{ node.outerHTML }}" model="{{ item }}"></html-render>
      </template>
    </template>
  </template>
  <script>
    Polymer({
      attached: function () {
        var nodes = this.$.content.getDistributedNodes();
        this.contentNodes = _.isArray(nodes) ? nodes : nodes.array();
        this.$.content.remove();
      }
    });
  </script>
</polymer-element>

Answer 3

使用Scott Miles＆＃39;解决方案，但包括<core-ajax>：

<rendered-collection url="/api/items">
  <template>
    <custom-element value="{{ }}"></custom-element>
  </template>
</rendered-collection>

与

<polymer-element name="rendered-collection" attributes="url">
  <template>
    <core-ajax auto
               url="{{ url }}"
               handleAs="json"
               response="{{ collection }}"></core-ajax>
    <content></content>
  </template>
  <script>
    Polymer({
      ready: function() {
        this.clientTemplate = this.querySelector('template');
        this.clientTemplate.bindingDelegate = new PolymerExpressions();
        this.clientTemplate.model = this;
        this.clientTemplate.setAttribute('repeat', '{{ collection }}');
      }
    });
  </script>
</polymer-element>

使用Polymer实现声明性集合渲染的最佳方法是什么？

3 个答案: